Ejemplo n.º 1
0
// Create a new label volume and post it to the test datastore.
// Each voxel in volume has sequential labels in X, Y, then Z order.
func (vol *labelVol) postLabelVolume(t *testing.T, uuid dvid.UUID, compression, roi string, startLabel uint64) {
	vol.makeLabelVolume(t, uuid, startLabel)

	apiStr := fmt.Sprintf("%snode/%s/%s/raw/0_1_2/%d_%d_%d/%d_%d_%d", server.WebAPIPath,
		uuid, vol.name, vol.nx, vol.ny, vol.nz, vol.offset[0], vol.offset[1], vol.offset[2])
	query := true

	var data []byte
	var err error
	switch compression {
	case "lz4":
		apiStr += "?compression=lz4"
		compressed := make([]byte, lz4.CompressBound(vol.data))
		var outSize int
		if outSize, err = lz4.Compress(vol.data, compressed); err != nil {
			t.Fatal(err)
		}
		data = compressed[:outSize]
	case "gzip":
		apiStr += "?compression=gzip"
		var buf bytes.Buffer
		gw := gzip.NewWriter(&buf)
		if _, err = gw.Write(vol.data); err != nil {
			t.Fatal(err)
		}
		data = buf.Bytes()
		if err = gw.Close(); err != nil {
			t.Fatal(err)
		}
	default:
		data = vol.data
		query = false
	}
	if roi != "" {
		if query {
			apiStr += "&roi=" + roi
		} else {
			apiStr += "?roi=" + roi
		}
	}
	server.TestHTTP(t, "POST", apiStr, bytes.NewBuffer(data))
}
Ejemplo n.º 2
0
// SerializeData serializes a slice of bytes using optional compression, checksum.
// Checksum will be ignored if the underlying compression already employs
// checksums, e.g., Gzip.
func SerializeData(data []byte, compress Compression, checksum Checksum) ([]byte, error) {
	if data == nil || len(data) == 0 {
		return []byte{}, nil
	}

	var buffer bytes.Buffer

	// Don't duplicate checksum if using Gzip, which already has checksum & length checks.
	if compress.format == Gzip {
		checksum = NoChecksum
	}

	// Store the requested compression and checksum
	format := EncodeSerializationFormat(compress, checksum)
	if err := binary.Write(&buffer, binary.LittleEndian, format); err != nil {
		return nil, err
	}

	// Handle compression if requested
	var err error
	var byteData []byte
	switch compress.format {
	case Uncompressed:
		byteData = data
	case Snappy:
		byteData = snappy.Encode(nil, data)
	case LZ4:
		origSize := uint32(len(data))
		byteData = make([]byte, lz4.CompressBound(data)+4)
		binary.LittleEndian.PutUint32(byteData[0:4], origSize)
		var outSize int
		outSize, err = lz4.Compress(data, byteData[4:])
		if err != nil {
			return nil, err
		}
		byteData = byteData[:4+outSize]
	case Gzip:
		var b bytes.Buffer
		w, err := gzip.NewWriterLevel(&b, int(compress.level))
		if err != nil {
			return nil, err
		}
		if _, err = w.Write(data); err != nil {
			return nil, err
		}
		if err = w.Close(); err != nil {
			return nil, err
		}
		byteData = b.Bytes()
	default:
		return nil, fmt.Errorf("Illegal compression (%s) during serialization", compress)
	}

	// Handle checksum if requested
	switch checksum {
	case NoChecksum:
	case CRC32:
		crcChecksum := crc32.ChecksumIEEE(byteData)
		if err := binary.Write(&buffer, binary.LittleEndian, crcChecksum); err != nil {
			return nil, err
		}
	default:
		return nil, fmt.Errorf("Illegal checksum (%s) in serialize.SerializeData()", checksum)
	}

	// Note the actual data is written last, after any checksum so we don't have to
	// worry about length when deserializing.
	if _, err := buffer.Write(byteData); err != nil {
		return nil, err
	}
	return buffer.Bytes(), nil
}
Ejemplo n.º 3
0
func (d *Data) serveVolume(w http.ResponseWriter, r *http.Request, geom *GoogleSubvolGeom, noblanks bool) error {
	// If it's outside, write blank tile unless user wants no blanks.
	if geom.outside {
		if noblanks {
			http.NotFound(w, r)
			return fmt.Errorf("Requested subvolume is outside of available volume.")
		}
		return nil
	}

	// If we are within volume, get data from Google.
	url, err := geom.GetURL(d.VolumeID, "")
	if err != nil {
		return err
	}

	timedLog := dvid.NewTimeLog()
	client, err := d.GetClient()
	if err != nil {
		dvid.Errorf("Can't get OAuth2 connection to Google: %v\n", err)
		return err
	}
	resp, err := client.Get(url)
	if err != nil {
		return err
	}
	timedLog.Infof("PROXY HTTP to Google: %s, returned response %d", url, resp.StatusCode)
	defer resp.Body.Close()

	// If it's on edge, we need to pad the subvolume to the requested size.
	if geom.edge {
		return fmt.Errorf("Googlevoxels subvolume GET does not pad data on edge at this time")
	}

	// If we aren't on edge or outside, our return status should be OK.
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("Unexpected status code %d on volume request (%q, volume id %q)", resp.StatusCode, d.DataName(), d.VolumeID)
	}

	w.Header().Set("Content-type", "application/octet-stream")

	queryStrings := r.URL.Query()
	compression := queryStrings.Get("compression")

	switch compression {
	case "lz4":
		// Decompress snappy
		sdata, err := ioutil.ReadAll(resp.Body)
		timedLog.Infof("Got snappy-encoded subvolume from Google, %d bytes\n", len(sdata))
		if err != nil {
			return err
		}
		data, err := snappy.Decode(nil, sdata)
		if err != nil {
			return err
		}
		// Recompress and transmit as lz4
		lz4data := make([]byte, lz4.CompressBound(data))
		outSize, err := lz4.Compress(data, lz4data)
		if err != nil {
			return err
		}
		if _, err := w.Write(lz4data[:outSize]); err != nil {
			return err
		}
		timedLog.Infof("Sent lz4-encoded subvolume from DVID, %d bytes\n", outSize)

	default: // "snappy"
		// Just stream data from Google
		respBytes := 0
		const BufferSize = 32 * 1024
		buf := make([]byte, BufferSize)
		for {
			n, err := resp.Body.Read(buf)
			respBytes += n
			eof := (err == io.EOF)
			if err != nil && !eof {
				return err
			}
			if _, err = w.Write(buf[:n]); err != nil {
				return err
			}
			if f, ok := w.(http.Flusher); ok {
				f.Flush()
			}
			if eof {
				break
			}
		}
		timedLog.Infof("Proxied snappy-encoded subvolume from Google, %d bytes\n", respBytes)
	}

	return nil
}
Ejemplo n.º 4
0
// ServeHTTP handles all incoming HTTP requests for this data.
func (d *Data) ServeHTTP(uuid dvid.UUID, ctx *datastore.VersionedCtx, w http.ResponseWriter, r *http.Request) {
	// TODO -- Refactor this method to break it up and make it simpler.  Use the web routing for the endpoints.

	timedLog := dvid.NewTimeLog()

	// Get the action (GET, POST)
	action := strings.ToLower(r.Method)
	switch action {
	case "get":
	case "post":
	case "delete":
	default:
		server.BadRequest(w, r, "labelblk only handles GET, POST, and DELETE HTTP verbs")
		return
	}

	// Break URL request into arguments
	url := r.URL.Path[len(server.WebAPIPath):]
	parts := strings.Split(url, "/")
	if len(parts[len(parts)-1]) == 0 {
		parts = parts[:len(parts)-1]
	}

	// Get query strings and possible roi
	var roiptr *imageblk.ROI
	queryValues := r.URL.Query()
	roiname := dvid.InstanceName(queryValues.Get("roi"))
	if len(roiname) != 0 {
		roiptr = new(imageblk.ROI)
	}

	// Handle POST on data -> setting of configuration
	if len(parts) == 3 && action == "post" {
		config, err := server.DecodeJSON(r)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		if err := d.ModifyConfig(config); err != nil {
			server.BadRequest(w, r, err)
			return
		}
		if err := datastore.SaveDataByUUID(uuid, d); err != nil {
			server.BadRequest(w, r, err)
			return
		}
		fmt.Fprintf(w, "Changed '%s' based on received configuration:\n%s\n", d.DataName(), config)
		return
	}

	if len(parts) < 4 {
		server.BadRequest(w, r, "Incomplete API request")
		return
	}

	// Process help and info.
	switch parts[3] {
	case "help":
		w.Header().Set("Content-Type", "text/plain")
		fmt.Fprintln(w, dtype.Help())

	case "metadata":
		jsonStr, err := d.NdDataMetadata()
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		w.Header().Set("Content-Type", "application/vnd.dvid-nd-data+json")
		fmt.Fprintln(w, jsonStr)

	case "info":
		jsonBytes, err := d.MarshalJSON()
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		fmt.Fprintf(w, string(jsonBytes))

	case "label":
		// GET <api URL>/node/<UUID>/<data name>/label/<coord>
		if len(parts) < 5 {
			server.BadRequest(w, r, "DVID requires coord to follow 'label' command")
			return
		}
		coord, err := dvid.StringToPoint(parts[4], "_")
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		label, err := d.GetLabelAtPoint(ctx.VersionID(), coord)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		w.Header().Set("Content-type", "application/json")
		jsonStr := fmt.Sprintf(`{"Label": %d}`, label)
		fmt.Fprintf(w, jsonStr)
		timedLog.Infof("HTTP %s: label at %s (%s)", r.Method, coord, r.URL)

	case "labels":
		// POST <api URL>/node/<UUID>/<data name>/labels
		if action != "post" {
			server.BadRequest(w, r, "Batch labels query must be a POST request")
			return
		}
		data, err := ioutil.ReadAll(r.Body)
		if err != nil {
			server.BadRequest(w, r, "Bad POSTed data for batch reverse query.  Should be JSON.")
			return
		}
		var coords []dvid.Point3d
		if err := json.Unmarshal(data, &coords); err != nil {
			server.BadRequest(w, r, fmt.Sprintf("Bad labels request JSON: %v", err))
			return
		}
		w.Header().Set("Content-type", "application/json")
		fmt.Fprintf(w, "[")
		sep := false
		for _, coord := range coords {
			label, err := d.GetLabelAtPoint(ctx.VersionID(), coord)
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}
			if sep {
				fmt.Fprintf(w, ",")
			}
			fmt.Fprintf(w, "%d", label)
			sep = true
		}
		fmt.Fprintf(w, "]")
		timedLog.Infof("HTTP batch label-at-point query (%d coordinates)", len(coords))

	case "blocks":
		// DELETE <api URL>/node/<UUID>/<data name>/blocks/<block coord>/<spanX>
		if len(parts) < 6 {
			server.BadRequest(w, r, "DVID requires starting block coord and # of blocks along X to follow 'blocks' endpoint.")
			return
		}
		blockCoord, err := dvid.StringToChunkPoint3d(parts[4], "_")
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		span, err := strconv.Atoi(parts[5])
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		if action != "delete" {
			server.BadRequest(w, r, "DVID currently accepts only DELETE on the 'blocks' endpoint")
			return
		}
		if err := d.DeleteBlocks(ctx, blockCoord, span); err != nil {
			server.BadRequest(w, r, err)
			return
		}
		timedLog.Infof("HTTP %s: delete %d blocks from %s (%s)", r.Method, span, blockCoord, r.URL)

	case "pseudocolor":
		if len(parts) < 7 {
			server.BadRequest(w, r, "'%s' must be followed by shape/size/offset", parts[3])
			return
		}
		shapeStr, sizeStr, offsetStr := parts[4], parts[5], parts[6]
		planeStr := dvid.DataShapeString(shapeStr)
		plane, err := planeStr.DataShape()
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		switch plane.ShapeDimensions() {
		case 2:
			slice, err := dvid.NewSliceFromStrings(planeStr, offsetStr, sizeStr, "_")
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}
			if action != "get" {
				server.BadRequest(w, r, "DVID does not permit 2d mutations, only 3d block-aligned stores")
				return
			}
			lbl, err := d.NewLabels(slice, nil)
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}
			if roiptr != nil {
				roiptr.Iter, err = roi.NewIterator(roiname, ctx.VersionID(), lbl)
				if err != nil {
					server.BadRequest(w, r, err)
					return
				}
			}
			img, err := d.GetImage(ctx.VersionID(), lbl, roiptr)
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}

			// Convert to pseudocolor
			pseudoColor, err := colorImage(img)
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}

			//dvid.ElapsedTime(dvid.Normal, startTime, "%s %s upto image formatting", op, slice)
			var formatStr string
			if len(parts) >= 8 {
				formatStr = parts[7]
			}
			err = dvid.WriteImageHttp(w, pseudoColor, formatStr)
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}
			timedLog.Infof("HTTP %s: %s (%s)", r.Method, plane, r.URL)
		default:
			server.BadRequest(w, r, "DVID currently supports only 2d pseudocolor image requests")
			return
		}

	case "raw", "isotropic":
		if len(parts) < 7 {
			server.BadRequest(w, r, "'%s' must be followed by shape/size/offset", parts[3])
			return
		}
		var isotropic bool = (parts[3] == "isotropic")
		shapeStr, sizeStr, offsetStr := parts[4], parts[5], parts[6]
		planeStr := dvid.DataShapeString(shapeStr)
		plane, err := planeStr.DataShape()
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		switch plane.ShapeDimensions() {
		case 2:
			slice, err := dvid.NewSliceFromStrings(planeStr, offsetStr, sizeStr, "_")
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}
			if action != "get" {
				server.BadRequest(w, r, "DVID does not permit 2d mutations, only 3d block-aligned stores")
				return
			}
			rawSlice, err := dvid.Isotropy2D(d.Properties.VoxelSize, slice, isotropic)
			lbl, err := d.NewLabels(rawSlice, nil)
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}
			if roiptr != nil {
				roiptr.Iter, err = roi.NewIterator(roiname, ctx.VersionID(), lbl)
				if err != nil {
					server.BadRequest(w, r, err)
					return
				}
			}
			img, err := d.GetImage(ctx.VersionID(), lbl, roiptr)
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}
			if isotropic {
				dstW := int(slice.Size().Value(0))
				dstH := int(slice.Size().Value(1))
				img, err = img.ScaleImage(dstW, dstH)
				if err != nil {
					server.BadRequest(w, r, err)
					return
				}
			}
			var formatStr string
			if len(parts) >= 8 {
				formatStr = parts[7]
			}
			//dvid.ElapsedTime(dvid.Normal, startTime, "%s %s upto image formatting", op, slice)
			err = dvid.WriteImageHttp(w, img.Get(), formatStr)
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}
			timedLog.Infof("HTTP %s: %s (%s)", r.Method, plane, r.URL)
		case 3:
			queryStrings := r.URL.Query()
			throttle := queryStrings.Get("throttle")
			if throttle == "true" || throttle == "on" {
				select {
				case <-server.Throttle:
					// Proceed with operation, returning throttle token to server at end.
					defer func() {
						server.Throttle <- 1
					}()
				default:
					throttleMsg := fmt.Sprintf("Server already running maximum of %d throttled operations",
						server.MaxThrottledOps)
					http.Error(w, throttleMsg, http.StatusServiceUnavailable)
					return
				}
			}
			compression := queryValues.Get("compression")
			subvol, err := dvid.NewSubvolumeFromStrings(offsetStr, sizeStr, "_")
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}
			if action == "get" {
				lbl, err := d.NewLabels(subvol, nil)
				if err != nil {
					server.BadRequest(w, r, err)
					return
				}
				if roiptr != nil {
					roiptr.Iter, err = roi.NewIterator(roiname, ctx.VersionID(), lbl)
					if err != nil {
						server.BadRequest(w, r, err)
						return
					}
				}
				data, err := d.GetVolume(ctx.VersionID(), lbl, roiptr)
				if err != nil {
					server.BadRequest(w, r, err)
					return
				}
				w.Header().Set("Content-type", "application/octet-stream")
				switch compression {
				case "":
					_, err = w.Write(data)
					if err != nil {
						server.BadRequest(w, r, err)
						return
					}
				case "lz4":
					compressed := make([]byte, lz4.CompressBound(data))
					var n, outSize int
					if outSize, err = lz4.Compress(data, compressed); err != nil {
						server.BadRequest(w, r, err)
						return
					}
					compressed = compressed[:outSize]
					if n, err = w.Write(compressed); err != nil {
						server.BadRequest(w, r, err)
						return
					}
					if n != outSize {
						errmsg := fmt.Sprintf("Only able to write %d of %d lz4 compressed bytes\n", n, outSize)
						dvid.Errorf(errmsg)
						server.BadRequest(w, r, errmsg)
						return
					}
				case "gzip":
					gw := gzip.NewWriter(w)
					if _, err = gw.Write(data); err != nil {
						server.BadRequest(w, r, err)
						return
					}
					if err = gw.Close(); err != nil {
						server.BadRequest(w, r, err)
						return
					}
				default:
					server.BadRequest(w, r, "unknown compression type %q", compression)
					return
				}
			} else {
				if isotropic {
					server.BadRequest(w, r, "can only POST 'raw' not 'isotropic' images")
					return
				}
				// Make sure vox is block-aligned
				if !dvid.BlockAligned(subvol, d.BlockSize()) {
					server.BadRequest(w, r, "cannot store labels in non-block aligned geometry %s -> %s", subvol.StartPoint(), subvol.EndPoint())
					return
				}

				var data []byte
				switch compression {
				case "":
					tlog := dvid.NewTimeLog()
					data, err = ioutil.ReadAll(r.Body)
					if err != nil {
						server.BadRequest(w, r, err)
						return
					}
					tlog.Debugf("read 3d uncompressed POST")
				case "lz4":
					tlog := dvid.NewTimeLog()
					data, err = ioutil.ReadAll(r.Body)
					if err != nil {
						server.BadRequest(w, r, err)
						return
					}
					if len(data) == 0 {
						server.BadRequest(w, r, "received 0 LZ4 compressed bytes")
						return
					}
					tlog.Debugf("read 3d lz4 POST")
					tlog = dvid.NewTimeLog()
					uncompressed := make([]byte, subvol.NumVoxels()*8)
					err = lz4.Uncompress(data, uncompressed)
					if err != nil {
						server.BadRequest(w, r, err)
						return
					}
					data = uncompressed
					tlog.Debugf("uncompressed 3d lz4 POST")
				case "gzip":
					tlog := dvid.NewTimeLog()
					gr, err := gzip.NewReader(r.Body)
					if err != nil {
						server.BadRequest(w, r, err)
						return
					}
					data, err = ioutil.ReadAll(gr)
					if err != nil {
						server.BadRequest(w, r, err)
						return
					}
					if err = gr.Close(); err != nil {
						server.BadRequest(w, r, err)
						return
					}
					tlog.Debugf("read and uncompress 3d gzip POST")
				default:
					server.BadRequest(w, r, "unknown compression type %q", compression)
					return
				}
				lbl, err := d.NewLabels(subvol, data)
				if err != nil {
					server.BadRequest(w, r, err)
					return
				}
				if roiptr != nil {
					roiptr.Iter, err = roi.NewIterator(roiname, ctx.VersionID(), lbl)
					if err != nil {
						server.BadRequest(w, r, err)
						return
					}
				}
				if err = d.PutVoxels(ctx.VersionID(), lbl.Voxels, roiptr); err != nil {
					server.BadRequest(w, r, err)
					return
				}
			}
			timedLog.Infof("HTTP %s: %s (%s)", r.Method, subvol, r.URL)
		default:
			server.BadRequest(w, r, "DVID currently supports shapes of only 2 and 3 dimensions")
			return
		}

	default:
		server.BadRequest(w, r, "Unrecognized API call %q for labelblk data %q.  See API help.",
			parts[3], d.DataName())
	}
}
Ejemplo n.º 5
0
// ServeHTTP handles all incoming HTTP requests for this data.
func (d *Data) ServeHTTP(uuid dvid.UUID, ctx *datastore.VersionedCtx, w http.ResponseWriter, r *http.Request) {
	timedLog := dvid.NewTimeLog()
	versionID := ctx.VersionID()

	// Get the action (GET, POST)
	action := strings.ToLower(r.Method)

	// Break URL request into arguments
	url := r.URL.Path[len(server.WebAPIPath):]
	parts := strings.Split(url, "/")
	if len(parts[len(parts)-1]) == 0 {
		parts = parts[:len(parts)-1]
	}

	// Handle POST on data -> setting of configuration
	if len(parts) == 3 && action == "put" {
		config, err := server.DecodeJSON(r)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		if err := d.ModifyConfig(config); err != nil {
			server.BadRequest(w, r, err)
			return
		}
		if err := datastore.SaveDataByUUID(uuid, d); err != nil {
			server.BadRequest(w, r, err)
			return
		}
		fmt.Fprintf(w, "Changed '%s' based on received configuration:\n%s\n", d.DataName(), config)
		return
	}

	if len(parts) < 4 {
		server.BadRequest(w, r, "Incomplete API request")
		return
	}

	// Process help and info.
	switch parts[3] {
	case "help":
		w.Header().Set("Content-Type", "text/plain")
		fmt.Fprintln(w, dtype.Help())

	case "info":
		jsonBytes, err := d.MarshalJSON()
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		fmt.Fprintf(w, string(jsonBytes))

	case "sparsevol":
		// GET <api URL>/node/<UUID>/<data name>/sparsevol/<label>
		// POST <api URL>/node/<UUID>/<data name>/sparsevol/<label>
		// HEAD <api URL>/node/<UUID>/<data name>/sparsevol/<label>
		if len(parts) < 5 {
			server.BadRequest(w, r, "ERROR: DVID requires label ID to follow 'sparsevol' command")
			return
		}
		label, err := strconv.ParseUint(parts[4], 10, 64)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		if label == 0 {
			server.BadRequest(w, r, "Label 0 is protected background value and cannot be used as sparse volume.\n")
			return
		}
		queryValues := r.URL.Query()
		var b Bounds
		b.VoxelBounds, err = dvid.BoundsFromQueryString(r)
		if err != nil {
			server.BadRequest(w, r, "Error parsing bounds from query string: %v\n", err)
			return
		}
		b.BlockBounds = b.VoxelBounds.Divide(d.BlockSize)
		b.Exact = true
		if queryValues.Get("exact") == "false" {
			b.Exact = false
		}

		compression := queryValues.Get("compression")

		switch action {
		case "get":
			data, err := GetSparseVol(ctx, label, b)
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}
			w.Header().Set("Content-type", "application/octet-stream")
			switch compression {
			case "":
				_, err = w.Write(data)
				if err != nil {
					server.BadRequest(w, r, err)
					return
				}
			case "lz4":
				compressed := make([]byte, lz4.CompressBound(data))
				var n, outSize int
				if outSize, err = lz4.Compress(data, compressed); err != nil {
					server.BadRequest(w, r, err)
					return
				}
				compressed = compressed[:outSize]
				if n, err = w.Write(compressed); err != nil {
					server.BadRequest(w, r, err)
					return
				}
				if n != outSize {
					errmsg := fmt.Sprintf("Only able to write %d of %d lz4 compressed bytes\n", n, outSize)
					dvid.Errorf(errmsg)
					server.BadRequest(w, r, errmsg)
					return
				}
			case "gzip":
				gw := gzip.NewWriter(w)
				if _, err = gw.Write(data); err != nil {
					server.BadRequest(w, r, err)
					return
				}
				if err = gw.Close(); err != nil {
					server.BadRequest(w, r, err)
					return
				}
			default:
				server.BadRequest(w, r, "unknown compression type %q", compression)
				return
			}

		case "head":
			w.Header().Set("Content-type", "text/html")
			found, err := FoundSparseVol(ctx, label, b)
			if err != nil {
				server.BadRequest(w, r, err)
				return
			}
			if found {
				w.WriteHeader(http.StatusOK)
			} else {
				w.WriteHeader(http.StatusNoContent)
			}
			return

		case "post":
			server.BadRequest(w, r, "POST of sparsevol not currently implemented\n")
			return
			// if err := d.PutSparseVol(versionID, label, r.Body); err != nil {
			// 	server.BadRequest(w, r, err)
			// 	return
			// }
		default:
			server.BadRequest(w, r, "Unable to handle HTTP action %s on sparsevol endpoint", action)
			return
		}
		timedLog.Infof("HTTP %s: sparsevol on label %d (%s)", r.Method, label, r.URL)

	case "sparsevol-by-point":
		// GET <api URL>/node/<UUID>/<data name>/sparsevol-by-point/<coord>
		if len(parts) < 5 {
			server.BadRequest(w, r, "ERROR: DVID requires coord to follow 'sparsevol-by-point' command")
			return
		}
		coord, err := dvid.StringToPoint(parts[4], "_")
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		source, err := d.GetSyncedLabelblk(versionID)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		label, err := source.GetLabelAtPoint(ctx.VersionID(), coord)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		if label == 0 {
			server.BadRequest(w, r, "Label 0 is protected background value and cannot be used as sparse volume.\n")
			return
		}
		data, err := GetSparseVol(ctx, label, Bounds{})
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		w.Header().Set("Content-type", "application/octet-stream")
		_, err = w.Write(data)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		timedLog.Infof("HTTP %s: sparsevol-by-point at %s (%s)", r.Method, coord, r.URL)

	case "sparsevol-coarse":
		// GET <api URL>/node/<UUID>/<data name>/sparsevol-coarse/<label>
		if len(parts) < 5 {
			server.BadRequest(w, r, "DVID requires label ID to follow 'sparsevol-coarse' command")
			return
		}
		label, err := strconv.ParseUint(parts[4], 10, 64)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		if label == 0 {
			server.BadRequest(w, r, "Label 0 is protected background value and cannot be used as sparse volume.\n")
			return
		}
		data, err := GetSparseCoarseVol(ctx, label)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		w.Header().Set("Content-type", "application/octet-stream")
		_, err = w.Write(data)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		timedLog.Infof("HTTP %s: sparsevol-coarse on label %d (%s)", r.Method, label, r.URL)

	case "maxlabel":
		// GET <api URL>/node/<UUID>/<data name>/maxlabel
		w.Header().Set("Content-Type", "application/json")
		switch action {
		case "get":
			maxlabel, ok := d.MaxLabel[versionID]
			if !ok {
				server.BadRequest(w, r, "No maximum label found for %s version %d\n", d.DataName(), versionID)
				return
			}
			fmt.Fprintf(w, "{%q: %d}", "maxlabel", maxlabel)
		default:
			server.BadRequest(w, r, "Unknown action %q requested: %s\n", action, r.URL)
			return
		}
		timedLog.Infof("HTTP maxlabel request (%s)", r.URL)

	case "nextlabel":
		// GET <api URL>/node/<UUID>/<data name>/nextlabel
		// POST <api URL>/node/<UUID>/<data name>/nextlabel
		w.Header().Set("Content-Type", "application/json")
		switch action {
		case "get":
			fmt.Fprintf(w, "{%q: %d}", "nextlabel", d.MaxRepoLabel+1)
		case "post":
			server.BadRequest(w, r, "POST on maxlabel is not supported yet.\n")
			return
		default:
			server.BadRequest(w, r, "Unknown action %q requested: %s\n", action, r.URL)
			return
		}
		timedLog.Infof("HTTP maxlabel request (%s)", r.URL)

	case "split":
		// POST <api URL>/node/<UUID>/<data name>/split/<label>
		if action != "post" {
			server.BadRequest(w, r, "Split requests must be POST actions.")
			return
		}
		if len(parts) < 5 {
			server.BadRequest(w, r, "ERROR: DVID requires label ID to follow 'split' command")
			return
		}
		fromLabel, err := strconv.ParseUint(parts[4], 10, 64)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		if fromLabel == 0 {
			server.BadRequest(w, r, "Label 0 is protected background value and cannot be used as sparse volume.\n")
			return
		}
		toLabel, err := d.SplitLabels(ctx.VersionID(), fromLabel, r.Body)
		if err != nil {
			server.BadRequest(w, r, fmt.Sprintf("split: %v", err))
			return
		}
		w.Header().Set("Content-Type", "application/json")
		fmt.Fprintf(w, "{%q: %d}", "label", toLabel)
		timedLog.Infof("HTTP split request (%s)", r.URL)

	case "split-coarse":
		// POST <api URL>/node/<UUID>/<data name>/split-coarse/<label>
		if action != "post" {
			server.BadRequest(w, r, "Split-coarse requests must be POST actions.")
			return
		}
		if len(parts) < 5 {
			server.BadRequest(w, r, "ERROR: DVID requires label ID to follow 'split' command")
			return
		}
		fromLabel, err := strconv.ParseUint(parts[4], 10, 64)
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		if fromLabel == 0 {
			server.BadRequest(w, r, "Label 0 is protected background value and cannot be used as sparse volume.\n")
			return
		}
		toLabel, err := d.SplitCoarseLabels(ctx.VersionID(), fromLabel, r.Body)
		if err != nil {
			server.BadRequest(w, r, fmt.Sprintf("split-coarse: %v", err))
			return
		}
		w.Header().Set("Content-Type", "application/json")
		fmt.Fprintf(w, "{%q: %d}", "label", toLabel)
		timedLog.Infof("HTTP split-coarse request (%s)", r.URL)

	case "merge":
		// POST <api URL>/node/<UUID>/<data name>/merge
		if action != "post" {
			server.BadRequest(w, r, "Merge requests must be POST actions.")
			return
		}
		data, err := ioutil.ReadAll(r.Body)
		if err != nil {
			server.BadRequest(w, r, "Bad POSTed data for merge.  Should be JSON.")
			return
		}
		var tuple labels.MergeTuple
		if err := json.Unmarshal(data, &tuple); err != nil {
			server.BadRequest(w, r, fmt.Sprintf("Bad merge op JSON: %v", err))
			return
		}
		mergeOp, err := tuple.Op()
		if err != nil {
			server.BadRequest(w, r, err)
			return
		}
		if err := d.MergeLabels(ctx.VersionID(), mergeOp); err != nil {
			server.BadRequest(w, r, fmt.Sprintf("Error on merge: %v", err))
			return
		}
		timedLog.Infof("HTTP merge request (%s)", r.URL)

	default:
		server.BadRequest(w, r, "Unrecognized API call %q for labelvol data %q.  See API help.",
			parts[3], d.DataName())
	}
}